Recently, server virtualization technology has become widespread and it is common to integrate a plurality of virtual servers on single hardware (physical server). Furthermore, its purpose is not only to reduce capital investment, but an information system can be flexibly operated, for example, by developing a technique to complete the introduction of a server to users by means of template management of a virtual server, which has been set, simply by creating a copy of a virtual disk used by the virtual server, or a technique to cancel hot spots by detecting the hot spots such as the occurrence of a failure or load unbalance and dynamically changing a logical configuration of the virtual server.
However, server virtualization is to introduce a new abstraction layer into a physical server; and accordingly, this might complicate configuration management of the physical server. For example, as compared to a case where a conventional server virtualization technique is not used, it has become difficult to understand which server uses which volume, based only on configuration information of the physical server and a storage apparatus.
As a result, it becomes inevitably necessary to have virtual server management software manage a connection relationship between storage areas and virtual servers that changes from moment to moment, and virtual server resource usage in these virtual servers. Also, an attempt has been made to extend functions of the virtual server management software in order to manage storage resources which are one of important components of the virtual servers. In order to do so, there is a method of making the virtual server management software have a function operating virtual storage areas and storage apparatuses.
For example, a function cooperating with storage, which is provided by a certain server virtualization software vender, is to equip the virtual server management software or server virtualization software with operation to send/receive commands, which can be interpreted by storage apparatuses made by a cooperative vender, based on cooperation with the storage vender. As a result, the storage apparatus can detect volumes used by the virtual servers and, therefore, can assume processing, such as copying of storage areas, that has been conventionally performed by the server virtualization software.
Furthermore, certain virtual server management software is equipped with a mechanism for managing storage apparatuses by using a storage management protocol SMI-S (Storage Management Initiative-Specification) which is an industry standard. As a result, a physical server that supports the SMI-S can specify volumes used by a virtual server in the physical server and utilize a copy function and thin provisioning function of storage apparatuses in cooperation with changes of the configuration of the virtual server.
The functions provided by the virtual server management software make it possible to migrate a virtual server to a different physical server and migrate a virtual storage area (virtual disk) of the virtual server to a different storage apparatus. This migration method is designed to avoid critical adverse effects on business activities performed by the virtual server by transferring data, which is used by the virtual server, from a transfer source to a transfer destination via a network between physical servers or a network between storage apparatuses (PTL 1).
Incidentally, it is known to treat a plurality of disk arrays of different models as if they were one disk array, by connecting another disk array (external storage) via a Fibre Channel interface and mapping its logical volumes (PTL 2).